Automatic rheostat



` Patented Dec. 6, |898.

E. T. WILKINSON.

AUTOMATIC RHEUSTAT.

(Applicltion led May 8, 1897.)

2 Sheets-Sheet I.

(No Modal.)

I# LUM ATTORNEYD me Nomus Pneus co. Hom-umu No. 6I5,4l8. Patented Dac. 6, |898. E. T. WILKINSUN. AUTOMATIC RHEOSTAT.

(Application led May S, 1897.)

2 Sheets-Sheet 2.

(No Model.)

fl NTOR TTORNEYC in: News Parsns co. Fumo-uma, wAsmuowN, u. c.

UNITED STATES PATENT OFFICE.

ELEAZER Arr. WILKINSON, or PHILADELPHIA, PENNSYLVANIA.

AUTOMATIC RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 61 5,418, dated December 6, 1898.

Application filed May 8, 1897. Serial No. 635,622. (No model.)

To all whom t may concern.'

Be it known that I, ELEAZER T. WILKIN- SON, a citizen of the United States, residing in the city and county of Philadelphia, State of Pennsylvania, have invented a new and useful Improvement in Automatic Rheostats, which improvement is fully set forth in the following specification and accompanying drawings.

My invention consists of an improved construction of automatic rheostat which is sensitive and automatically operative under all conditions, the feature of which is the automatic movement, .electrically controlled, of mechanisms which, acting as conductors, throw in or ont of circuit of the fields of the dynamo the resistance-coils attached to segments B' and C', D', E', and F'.

It further consists of anovel means for reducing friction to a minimum in certain portions of the rheostat.

It further consists of novel details of construction, all as will be hereinafter set forth, and fully pointed out in the claims.

Figure l represents a diagrammatic View of an automatic rheostat embodying my invention. Fig. 2 represents a diagrammatic view showinganother embodiment of the principle of my invention.

Referring iirst to Fig. l, A and B designate conductors leading from and to an alternating-current converter, said conductors being connected'to the solenoid C, which latter is provided with an armature D, the latter having suitable connection to the lever E, which is fulcrumed at the point F and provided wi th a counterbalance Gr.

H designates a needle which is suspended from the lever E and adapted to oscillate in unison therewith, wherefrom it will be seen that any variation of the current passing over the wires A B to the auxiliary solenoid C will cause a movement of the armature D, thereby actuating said lever.

The needle H will contact in one or the other of its extreme positions with the terminals J or K, said needle contacting with the terminal J in case of a rise above the normal and with the terminal K if below normal, thereby closing the circuits of t-he respective relays L and M, which are preferably connected and constructed substantially as shown and in electrical connection with a battery J X, Wherebythe armature with respect to relay will be magnetized sufiiciently to pick up the levers LX or lV X, which close the circuit N and P on the points Nx or PX, which maybe of carbon,

platinum, or other suitable material.

The function of the circuits N and P is to cause the working solenoids P2 and Q to actuate in the proper direction the armature R, which latter has a connection S therefrom to the lever T, which is fulcrumed at U. V designates a rod depending` from said armature and having a piston WV on the end thereof, said piston reciprocating in the cylinder or dash-pot Y, iilled with oil X or other suitable material, whereby motion of the armature R is steadied. i

Z designates the head or extremity of the lever T, in which is mounted the strip A', which carries the roller B', which travels on the segments C' D' E F', the., which have suitable insulation therebetween, said segments having the resistance-coils G' H' J',&c., extending therebetween and of sufficient size to introduce the desired resistance into the fields of the dynamo.

The windings of the working solenoids P2 and Q are in series from the to poles of the exciting-dynamo, and the segments C' D' E' F', tbc., are in series with wires running from the exciter to the iield of the alternating-current machine.

The lever T and the roller B', with their several connections and attachments, form an electrical conductor, which is used to affect the current in the iields of the alternating-current machine by bringing into circuit the resistance-coils connected with the seg- -ments C' D' E', tbc., through the wire BX,

connected at Ax with the lever T.

lVhen it is desired to use my invention in connection with a direct-current machine, I employ the construction seen in Fig. 2, in which L' designates a dynamo and M' N' the conductors leading therefrom to and from the auxiliary solenoid P', which has an armature Q', from which leads a connection to the lever R', suitably fulcrumed and provided With the needle S', by means of which electrical connection is made between the points T' or U', caused by any variation of electr-emotive force.

ICO

V and W' designate wires leading from the points T U to the relays X and Y', respectively, which instead of being worked by a battery-current, as shown in Fig.1, are wound in series with sufficient resistance Z' to reduce to a minimum the spark in the contact between S and U or S and T across the terminals from -lto A2 B2 designate the circuits to be closed by the relays X' and Y', respectively, and leading to the solenoids C2 D2, respectively, which latter are arranged side by side and each provided with an armature E2 F2, respectively, to which are attached dash-pots G2 G2, as already described.

H2 J 2 designate rods (preferably insulated) attached to the armatures E2 F2 and carrying the racks L2 M2, which mesh with the teeth P2 Q2, respectively, of the gear or pinion P3, which is journaled at S2 and has the f arm T2 connected therewith, said racks being held in proper position relative'to their pinion by means of the flanged revolving rollers R2.

U2 designates a roller pivotally supported from near the upper extremity of the arm T2 and adapted to travel over the segments V2, which are separated by suitable insulation and are each connected by the resistancecoils 72, it being evident that the segments in the present instance are in series with the field-winding of the dynamo, as will be seen by following out the connections therebetween.

The lever T2 and the roller U2, with their several connections and attachments, form an electrical conductor and are used to affect the current in the fields of the dynamo by bringing into circuit the resistance-coils connected with the segments V2 through the wire BY, connected at AY with the lever T2.

The operation is as follows: The moving of the lever T or T2 is effected by means of working solenoids lX Q or C2D2, respectively, and the action of the above solenoids is determined by means of the auxiliary solenoids C or P', the function of the latter being to move the lever, with the attached needle, a short space, it being evident that a very slight change of voltage is sufficient to do this.

Especial attention is called to the feature of the employment of the roller B and U2 as a means of connection between the arm T and T2 and the segments C D' E', &c., and V2, respectively, since by these means friction is reduced to a minimum, and the action of the workingsolenoids upon the lever T or T2, which is effected by means of the rod S or by the racks L2 M2, and the contiguous pinion P2, attached to or part of the lever T2, will be very sensitive in every instance by reason of the absence of friction between the contact device and the segments on which it travels, by reason of which the greatest efficiency is attained. Y

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. In a rheostat, a series of segments insulated from each other and provided with resistancecoils, a lever suitably fulcrumed and carryinga contact-roller for said segments, an armature connected with said lever, circuits with working solenoids therein actuating said armature, a solenoid with conductors leading thereto and provided with an armature, a pivoted lever connected with said armature and having a depending needle and relays in said solenoid-circuits having terminals adapted to be in contact with said needle, said relays having armatures for opening or closing said circuits.

2. In a rheostat, a plurality of workin g solenoids arranged side by side, armatures therefor, rods carrying racks and connected to said armatures, a pinion engaging said racks, means for keeping said racks and pinions in mesh, a lever attached to said pinion, a contact-roller carried by said lever together forming an electrical conductor, adapted to travel over segments, insulated from each other and provided with resistancecoils, together with means for actuating said armatures upon any variation of electronictive force.

3. In a rheostat, a series of insulated segments provided with resistance-coils, a pivoted lever carrying a roller contacting with said segments, an armature connected with said lever and provided with a stem having means connected therewith for steadying thc movement of said armature, circuits with workin g solenoids therein for actuating said armature, a solenoid with conductors leading thereto and provided with an armature having a pivoted lever with a depending needle, said first-mentioned solenoid-circuits having relays with terminals adapted to be in contact with said needle.

ELEAZER T. WILKINSON.

lVitnesses:

E.' H. FAIRBANKS, WM. C. Winnnnsnnim. 

